


blue flame

by corsica



Category: Fate/Grand Order
Genre: Begging, Blow Jobs, Deepthroating, Established Relationship, F/M, Plot What Plot/Porn Without Plot, Riding, Teasing, at the very least karna gets wrecked, ritsuka takes the lead for most of this but i dont think this counts as femdom
Language: English
Status: Completed
Published: 2021-02-07
Updated: 2021-02-07
Packaged: 2021-03-13 06:01:43
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,395
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29273637
Author URL: https://archiveofourown.org/users/corsica/pseuds/corsica
Summary: She wants to see him burn for her.
Relationships: Female Fujimaru Ritsuka/Karna | Lancer, Fujimaru Ritsuka/Karna | Lancer of Red
Comments: 8
Kudos: 18





	blue flame

**Author's Note:**

> continuing my quest of filling this pairing tag my own damn self

Karna blinks up at her.

“...Is that—.”

“The shirt you wore last year on Valentine's Day when you made that cake for me? Yes,” Ritsuka sits straddled on him, wearing that, the earrings he made for her, and nothing else, “...When I was in school, some of the girls I talked to would say how their boyfriends thought it was sexy whenever they wore their shirts and nothing else, because they liked how much bigger their clothes looked on them. You don't own a lot of clothes, so...I didn't have a lot to pick from.”

Karna's eyes zero in on the sizable strip of bare skin visible by way of her not buttoning up the button-down. The shirt is definitely oversized on her; the hem goes down to her mid-thigh and the sleeves cover her fingers to the second knuckle—and Karna knows he's not even particularly bulky, Ritsuka is just _that_ small. It hardly even feels like there's a weight on him as she sits atop him.

She drums her fingers nervously against his chest.

“Well...do you like it?”

He scans her thoroughly—down, pausing to stare at her bare thighs, before going back up—and realizes that, yes, this is definitely doing something for him.

“I do,” his finger traces down the exposed plane of skin, from her collarbone to her bellybutton, passing between her breasts, and she shivers, “Is this what you meant when you said you wanted to do something special for me?”

“This is part of it, yeah,” she reaches for his hand, and gently takes it off her chest, placing it back down on the bed by his side, “But it goes further than that.”

Ritsuka leans down and nips at a spot beneath his jaw. His toes curl, breath hitching simultaneously.

“I want to make you feel good, Karna. The way you treat me, I want to give that to you, too,” her hands cup the sides of his face as she presses her lips to his, “So, let me take care of you for tonight. Let me give you what you give me,” he digs the tips of his fingers into her sheets as she kisses down his neck, “Okay?”

His mind is already becoming hazy when she pulls back, staring down at him expectantly.

“I...understand,” his voice is strained, slightly breathy, and his eyes drift down to his hands, stuck motionless at his sides, “Can I touch you?”

“Of course,” she takes his hands and places them on her hips, “But keep it to my hips or my waist. This is about _you.”_

Karna stares off to the side with an unsure look on his face, “I'm not sure how comfortable I am with you doing everything...”

“Karnaaa,” she chides, in a sing-song tone of voice, “I really want to do this,” she kisses another line up his neck, and the nip she gave him earlier turns into a bite, garnering a stronger reaction of a moan tempered by closed lips, “So if it has to be, take it as an order to lean back and enjoy yourself,” he closes his eyes, and his cheeks heat up, “Besides, you were a King once, right?”

Yes, I— _mh,”_ he's cut off by her placing her hands on his shoulders and dipping down to kiss him, tongue winding around his, her breath warm against his lips during their brief moments of parting for air, “I was, but I don't know how that's relevant.”

Ritsuka slides her hands up from his shoulders to his face, cupping it once more, and he moves his hands to hold onto her hips from beneath the shirt, fingers sinking into the soft, plush skin as her mouth moves insistently against his, dragging out quiet, pleased moans from him. He meets her beat for beat, though, savoring the whimpers he's able to drive from her with his tongue alone, thumbs massaging into her hip bones as his name comes out of her in a gentle sigh.

Her forehead touches his when she finally breaks apart, and she has a teasing, playful smile on her face.

“Consider this a show of appreciation, my _Angaraja.”_

Her lips cover his before he's able to respond. It doesn't matter what he had wanted to say, anyway—she draws out the responses she wants from him as she mouths at his neck. Her teeth scrape against his skin, against long-memorized spots that have him writhing beneath her before he can stop himself, tightly closed lips parting to release gentle noises of pleasure. His hands fall limply to the bed as she begins to descend down his body, bursts of red blooming on his pale skin in her wake until she reaches the jagged edge where white meets black.

Even as his skin changes tone, too dark for any marks to properly appear, that's hardly a reason for her to stop. Ritsuka can see the way he grasps for her sheets, twisting the cotton in his hands as she presses her lips against his stomach, teeth and tongue biting and tracing along onyx skin. The fire he holds within him crackles and grows. She wants to see him burning for her.

By the time she reaches the only bit of golden armor he still has on, for modesty's sake, her impatience is obvious. Karna lets his armor fade into glimmers of mana, and before it fully dissipates into the air, before he is able to feel any of his usual hesitation at allowing himself to be treated this way, she tucks her hair back behind her ear, lets her hands settle on his thighs, and swallows him to the back of her throat without warning. It rips a moan out of Karna that fills up the room with its noise before he even has the chance to choke it back, and Ritsuka relishes the victory, as, even with his hand now shoved up against his mouth, she can still hear the sound of his desperate, shaky breaths. Gold glints in the light of the room from his hand as it clenches tighter, nails nearly shredding the fabric beneath him, and she lifts herself off of him slowly, dragging her tongue against him and gasping quietly for air when she's completely off. His hand feels like an inferno when she reaches for it, coaxing him to let go of her sheets and grasp onto her hair.

Red and swollen lips wrap around him, taking the head in her mouth and going no further. Her tongue laves against him with long, slow laps, eagerly tasting what beads out of the tip as Karna tries and fails to bite back a hiss. She moans, and curls her fingers around him—Karna is a being of pure ether. A Servant's biology is just a facsimile of a human's, and she enjoys the fact that mana does not taste salty.

He removes his hand from his face, and as he places both against her head, Ritsuka can feel how hard he's trembling. She stops, blinks in confusion as he starts to comb back her hair, but it dawns on her that he is gathering her hair out of her face and eyes. He holds it back with one hand while the other makes its way back to where it was against his mouth. Ritsuka breathes out a little laugh; in thanks, she gives his thigh a small squeeze.

The sound of his soft panting grows louder as she gradually begins to take more and more of his length into her mouth. Halfway down, her name comes out of him in a staggered exhale. When her lips reach the base, she goes still, her hands resting on his thighs and kneading his skin as she savors the sounds he makes. His hand is not held quite so firmly to his mouth, fingers spread and leaving wide spaces as he breathes in, out, chest heaving up, then down, as he futilely attempts to collect himself. She can feel him staring down at her through eyes just barely cracked open. Sharp, clear pools of crystalline blue have become nothing more than a sliver around his dilated pupils.

She still does not move. Karna's hand tugs lightly at her hair; his typically endless patience is starting to fray.

“...Rituska,” his eyes shut firmly, a tight, desperate edge to the sound of his voice, “...please.”

_Oh._

Electricity shoots down her spine. Ritsuka moans around him, and he breathes out one of his own, steam wafting in the air as he exhales.

...She had no idea she would like the sound of him begging this much.

It's intoxicating.

He has all the strength in the world, yet he's never looked so powerless. All because of her.

There's no reason for her to not oblige him. Spurred on, her head bobs, slow at first before she builds up a fluid pace. He grabs hold of her hair tighter, lets his head fall back against the small nest of pillows Ritsuka has on her bed. His tightly-closed mouth does hardly anything to muffle the sounds she pulls out of him. It's eventually a lost cause entirely; she starts to hum around him, and any sense of shame has faded as he gasps out her name with every other breath. She rubs up and down his thighs as she feels how hard he's shaking, how his heat swelters and licks at the palms of her hands.

“Karna,” she swipes her tongue from base to tip, eyes flicking up to look at him, “Stop holding back.”

When she takes the head into her mouth, lips forming a tight ring as her tongue curls around him, his climax does not take her by surprise, his stomach tensing and his hips rolling up into her mouth. Quiet panting turns into staggered, heavy gasping, and his hand falls from the top of her head. Ritsuka pushes a lock of now-loose hair behind her ear while she licks him clean.

He's still dazed, but his hips twitch and his brow furrows in response to what she's doing. It takes a great deal of effort, but he's able to blink open his eyes and look down on her, and he flusters immediately when he sees what she's doing.

“R—Ritsuka, that's...” she kisses against the tip, tongue darting out to tease him, _“Nnh...”_

She pulls away and crawls up his body, attaching her lips to his neck. One finger lightly runs up his length; Ritsuka knows that once is rarely enough for a Servant, and never enough for him—despite what he says when he stops himself for her own sake—so she isn't surprised as she feels just how hard he still is.

“You're trembling,” her lips trail to the hollow of his neck to suck another mark, fingers gently stroking him, “It feels good, doesn't it?”

With how preoccupied his voice is, moaning in response to what she's doing with her fingers and hand and lips and teeth and tongue, all he's able to do is give her is a slight, simple nod.

Even though this has been wholly about him, there is a throb between her legs that is becoming difficult to ignore. She sits up straight. Licks the taste of him off her fingers. There is nothing she wants more than to sink down onto him, but his eyes are closed and he isn't looking at her, and that needs to be fixed.

Both of her hands move to his face. Gold lines glint in the light once more as she coaxes his hand off of his mouth, twining their fingers together briefly to squeeze his heated hand. He is panting, slowly, softly, and there is a thin sheen of sweat on his face. Pale white has dark splotches of crimson staining it, on his cheeks, up to the tips of his ears, on his lips—the bottom of which has turned swollen from how much he has worried it between his teeth. Her hands cup his jaw in a silent request for him to open his eyes.

He does. They slowly crack open as his brow knits together.

He has never looked more desperate for her. The Son of the Sun God shines so brightly, and unravels so beautifully.

Ritsuka leans forward, presses her lips to his in a dizzying rush. Her head feels like it's spinning. She hardly has the state of mind to properly kiss him, mouths meeting gracelessly, their want for each other laid bare. Taking a pause to breathe feels like too long spent away, and their breath is hot as it mingles together only for a second before they're drawn into each other again, all lips and teeth and tongues. Karna's hands find purchase on her soft thighs, hands leaving a scalding, smoldering path on her skin as he slides them up to dig his fingers into her hips.

The need for her that she sees in his eyes only becomes more palpable as she breaks away. Ritsuka wraps her fingers around him as she lifts herself up, and she feels his nails scrape hotly against her.

“Don't take your eyes off me.”

There is very little resistance as he pushes inside of her. Her fingers let go of him, resting on his stomach, as she further lowers herself, until both of her palms are pressed flat once he's buried fully within her. Blood trickles up from her bottom lip from where her teeth have so firmly bitten in, and Ritsuka whimpers, because he is always so _good._

Karna breaks, and surges forward, hands shaking as they stay glued to her hips, tasting copper as the blood smears against his mouth. Ritsuka runs her hands up from his stomach to his chest, going with the momentum as she pushes him back down because she refuses to break the kiss. He is sweltering as her fingers trace down his arms, up his wrists, to his hands, breaking the iron grip he has on her and entwining their fingers together. When the kiss breaks, he swipes his tongue over his lips to lick away the blood.

An amused little smile plays at her lips, and she grinds down on him while she sucks at his neck. Her hands pin his against the pillows.

“Stay put.”

Any frustration he may have been feeling is pacified quickly as she kisses him, swallowing down the little gasp he makes as she clenches around him. Ritsuka is entirely unhurried in her pace, purposefully drawing out each downward motion and tensing around him. His hands are shaking harder than they ever have as she keeps them held to her pillows. Karna could so easily overpower her, but even as the pauses between the rise and fall of her hips grow longer and longer, Ritsuka raising up high before she takes him deep inside her again, letting him feel every bit of wet heat as she envelops him, he stays put. He is more breathing harshly against her lips than actually kissing her back, but he stays put.

She yearns to go faster, to chase her own high, but there's a greedy feeling that's sunk its claws into her.

One more time. She wants to hear him beg for her touch one more time.

His brow furrows and he makes a noise of confusion into the kiss as she completely raises off of him. Confusion abruptly turns to agonized realization as she rubs her slit against him, sliding in a steady, constant, back-and-forth rhythm without allowing him to go inside of her. The wide-eyed look of innocence she gives him is severely undercut by how dark her gaze is and how hard she's breathing.

He is pleading with his eyes, but that's not good enough. When she moves in to push her tongue into his mouth, running it along his own as she just barely takes the tip of him inside of her, that finally gets her what she wants.

“Please,” he begs into the kiss, and his hands grip hers so tightly it hurts, _“Please.”_

She sinks back down as soon as the words leave his mouth, and it is a relief to the both of them. The slow pace is thrown to the side, building rapidly, and her hands break from his to grab onto his shoulders to better balance herself. Karna takes to holding onto her hips again, guiding her down as he thrusts up into her. It is a routine so practiced there is almost no time at all until they are moving in sync.

Ritsuka gives him one last, lingering kiss before she straightens up, arching her back in ecstasy as he gives an extended roll of his hips. Her hands shake as she places them on his stomach, hair falling in front of her face as her head tips down in pleasure. The sound of her breathy, gasping moans only gets louder. She spreads her legs wider, nails scratching unseen lines into his abdomen and crying out as he bucks into her. As she raises her head, her eyes meet his; he has followed what she asked him to do, his eyes never once straying away from her body. The flush on his face has crawled down to his neck as he watches her silently.

Her palm slides up to press against his chest, against his wildly beating heart. His heat is scorching, hotter than a blue flame. He's burning for her.

Ritsuka can feel her own heart thundering against her ribcage.

She's burning for him.

“...Touch me,” she breathes out, “Touch me, touch me, touch me, touch me _touch me touch me touch me touch me touch me—.”_

Karna rushes up and crushes his lips to hers. His hands leave her hips to yank off the shirt she wears, but the red imprints of his fingers and palms remain. As he places his hands all over her body, his touch sears into her skin. Ritsuka scratches bleeding lines down his back as he kisses her, frantic and sharp and _hot_ and he rocks into her harder than he ever has before, stealing her breath with every thrust. There is no more fluidity. It's animalistic; pure, raw desire.

Ritsuka feels feverish. Her moans and her breaths come out simultaneously, Karna's name becoming the new sound of her exhales. He's like a fire, engulfing her and consuming her and she holds onto him tighter, digs her nails into him deeper as he pulls her down onto him every time his hips jerk. When he tangles his fingers in her hair, carefully tilting her head to the side so he can bury his teeth in her neck, Ritsuka curls her toes and cries out for him to go faster, harder, to _do it again._ Steam releases when he exhales before he's going faster, harder, roughly sinking his teeth into her neck over and over again, and they both know neither will last much longer.

Their lips meet as it all peaks to a finale, and Ritsuka whines into his mouth as she comes. His hips rut into her as he bites down on her lower lip, emptying himself inside of her. Ritsuka falls against him, feels the boiling heat of his body gradually die back down as he securely wraps his arms around her, his own panting off-tempo from Ritsuka's.

They're both silent as Karna carefully removes her, leaning over her as he lays her down on her bed. Her hair fans out against her pillows as her eyes open hazily to look at him. Karna's eyes briefly land on where his spend begins to slowly seep out from between her legs before trailing up to the multiple imprints of his hands on her torso, hips, and arms.

“I like them.”

Ritsuka's voice is a low murmur, pulling him out of his reverie before he can fall too deeply. She reaches up to draw him down to kiss him.

“I like knowing,” she whispers against his lips, “how hot I can make you burn.”

Her legs wrap around his waist as she releases his bottom lip from between her teeth.

“And...”

Her hands curl around his shoulders, heat simmering beneath her palms.

“I want to see it again.”

He pushes into her, covers her mouth with his, and burns for her.


End file.
